Bioprecipitation, the concept of rain-making bacteria, was proposed by David Sands from Montana State University. Such microbes – called ice nucleators – are found in rain, snow, HP Pavilion dm4-1008tu Battery and hail throughout the world. These bacteria may be part of a constant feedback between terrestrial ecosystems and clouds and may even have evolved the ability to promote rainstorms as a means of dispersal. They may rely on the rainfall to spread to new habitats, much as some plants rely on windblown pollen grainsHP Pavilion dm4-1008tx Battery.

High family A cirrus uncinus and cirrus fibratus upper-left merging into cirrostratus fibratus with some higher cirrocumulus floccus upper right. HP G62-a25EA Battery

High clouds form between 10,000 and 25,000 ft (3,000 and 7,600 m) in the polar regions, 16,500 and 40,000 ft (5,000 and 12,200 m) in the temperate regions and 20,000 and 60,000 ft (6,100 and 18,300 m) in the tropical region. HP G62-a25SA Battery It is the only height range family that includes genera from all three physical categories.[27]

Genus cirrus (Ci): Fibrous wisps of delicate white ice crystal cloud that show up clearly against the blue sky. HP G62-a26SA Battery Cirrus clouds are generally non-convective except castellanus and floccus species. They often form along a high altitude jetstream and at the very leading edge of a frontal or low pressure disturbance where they may merge into cirrostratus. HP G62-a27SA Battery

Species cirrus fibratus (Ci fib): Fibrous cirrus with no tufts or hooks (CH1).

Genus cirrocumulus (Cc): A cloud layer of limited convection composed of ice crystals or supercooled water droplets appearing as small white rounded masses or flakes in groups or lines with ripples like sand on a beach (CH9 for all species). HP G62-a29SA Battery They occasionally form alongside cirrus or cirrostratus clouds at the very leading edge of an active weather system.